(S)-4-Benzyl-2-oxazolidinone → 4-Benzyl-3-(2-cyclohexyl-acetyl)-oxazolidin-2-one

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Reaction Steps

Thionyl chloride (20.0 mL) was added dropwise to cyclohexyl acetic acid (10.0 g, 70 mmol). After cessation of gas evolution, the reaction mixture was heated to reflux overnight. The reaction mixture was then concentrated in vacuo to yield cyclohexyl acetyl chloride. To a solution of (S)-(−)-4-benzyl-2-oxazolidinone (11.6 g, 65 mmol) in THF (130 mL) at −60° C. was added 1.6 M n-butyl lithium (42 mL, 67 mmol), dropwise, and the reaction mixture was stirred for 0.5 h. To the resulting solution was then added the cyclohexylacetyl chloride, and the resulting mixture was stirred at 0° C. for 2 h. The reaction was quenched with aqueous saturated NaHCO3 solution and extracted with ethyl acetate. The organic layer was dried (MgSO4) and concentrated until a slurry was formed. The slurry was filtered and washed with cold diethyl ether. The filtrate was re-concentrated to yield a solid. The combined solid, 4-benzyl-3-(2-cyclohexyl-acetyl)-oxazolidin-2-one, was dried in vacuo.

Provenance & Evidence